| 摘要 |
There is provided an electric power steering apparatus which includes a monitoring/controlling means that monitors a failure of a CPU, and controls a drive signal for driving a motor at the time of the failure of the CPU, wherein the monitoring/controlling means has a first control mode for suspending driving of the motor, and a second control mode for continuously controlling the motor with a provisional drive signal, in place of and for restricting the drive signal from the CPU; and wherein, when the monitoring/controlling means detects the failure of the CPU, the monitoring/controlling means selects the second control mode to thereby continue controlling the motor with the provisional drive signal in place of the drive signal from the CPU, and then selects, after the controlling in the second control mode, the first control mode to thereby suspend driving of the motor. |
| 主权项 |
1. An electric power steering apparatus which comprises:
a steering torque sensor that detects a steering torque applied to a steering wheel by a driver; a motor that provides power to a steering system to assist a steering force of the driver; a central processing unit (CPU) that outputs a drive signal for driving the motor, according to the steering torque detected by the steering torque sensor; a monitoring/controlling means that monitors a failure of the CPU and controls the drive signal for driving the motor at the time of the failure of the CPU; and an interlock circuit which is connected to the CPU, wherein the monitoring/controlling means has a first control mode for suspending driving of the motor, and a second control mode for continuously controlling the motor with a provisional drive signal, in place of and for restricting the drive signal from the CPU; wherein, when the monitoring/controlling means detects the failure of the CPU, the monitoring/controlling means selects the second control mode to thereby continue controlling the motor with the provisional drive signal in place of the drive signal from the CPU, and after the second control mode, the monitoring/controlling means switches to the first control mode to suspend driving of the motor, wherein the interlock circuit has a drive permitted region and a drive prohibited region with respect to a relationship between the steering torque and the drive signal output by the CPU, so that, when the steering torque and the drive signal fall within the drive permitted region, the interlock circuit transmits the drive signal in an unchanged form, and when the steering torque and the drive signal fall within the drive prohibited region, the interlock circuit adds a restriction on the drive signal so as to restrict the drive signal outside of the drive prohibited region, wherein, when the monitoring/controlling means selects the second control mode to continue controlling the motor with the provisional drive signal, the provisional drive signal is further restricted by the interlock circuit such that when the provisional drive signal is in the drive prohibited region, the provisional drive signal is adjusted to the drive permitted region, and wherein the CPU and the monitoring and controlling circuit continuously communicate with each other to determine whether respective operations of the other are normal. |
